Surprisingly, AI has an excellent help file (depending on which version you have). AI CS4, for example describes the steps you need to make on page 77.

You can also open your browser and direct it to Google (just because I hate Bing...) and typing in "vectorizer". You'll find results where you can vectorize your artwork over the web just by uploading your artwork - for free.

If you want perfect quality, however, you will ALWAYS have to re-trace your image by hand, using the pen tool, since vectorizers never create perfect results (again, depending on what does "perfect" mean to you).